The present invention relates generally to elevator links (bails) and more particularly to a method and apparatus for varying the length of elevator links composed of multi-piece sections which provide for adjustable lengths and tonnage capacities, and for interchangeable link ends and adapters, and for such other structures and methods as may be herein disclosed.
In general, elevator links (also known as bails) are attached between the elevator and the traveling block of a drilling rig. The links connect the elevator to the hook of the traveling block which hangs on a number of steel cables from the crown block in the top of the drilling rig. These links are used for linking drill pipe, casing, and tubing, and for lowering them into the hole. The elevator links bear the weight of the drill string as does the elevator swivel.
Traditionally, one-piece elevator links comprise a shank with an eye at each end of the shank manufactured as a single piece from alloy steel or other well known suitable materials. Links are commonly produced in set lengths. Links are also commonly designed and produced to be capable of supporting a given, set tonnage. The interchangeability and connectivity of links, elevators, and hooks are based on tonnage size classes. There is thus a need for elevator links of various lengths as well as for elevator links capable of supporting various tonnage loads. The length and tonnage required will, of course, vary with the drilling and equipment requirements of a particular job or undertaking.
Conventionally, links have been constructed as a unitary piece. Each pair of links are constructed to meet certain set tonnage requirements, such as being capable of supporting 500, 750, or 1000 tons. The links are also manufactured in certain given or set lengths such as 12 feet.
Consequently, certain lengths and tonnage capacities are often manufactured in greater abundance than other set lengths or tonnages. Depending on drilling demands in a particular drilling field, a shortage of certain lengths, tonnage capacities, or both may occur. At times a drilling site in a region may require links, for example, of twenty-one feet, while the primarily available links may be twelve feet in length.
Thus, it would be a benefit to have a method for construction and producing links of various length and tonnage capacities on relatively short notice.
Pursuant to the foregoing, it may be regarded as an object of the present invention to overcome the deficiencies of and provide for improvements in the state of the prior art as described above and as may be known to those skilled in the art.
It is thus an object of the present invention to provide construction and producing links of various length and tonnage capacities on relatively short notice.
Still further objects may be recognized and become apparent upon consideration of the following specification, taken as a whole, in conjunction with the appended drawings and claims, wherein by way of illustration and example, an embodiment of the present invention is disclosed.
A multi-piece elevator link, which may be of variable length or capacity or both, is produced by cutting a unitary link into two or more parts and connecting different combinations of shanks and link ends to form the desired elevator link. Rotation of the link ends with respect to the shank may be prevented by a variety of means. For example, various threading, cross pins, locking mechanisms, interference fits, keys, hooks and the like may be employed. Various adapters may be employed between the shank and link ends to provide varying connections such as those produced by various threads, cross pins, ball-and-socket combinations, grooves and retaining rings, interference fits, keys, hooks and the like.
A method of dividing a unitary elevator link into two or more parts and providing the differing shank or link end or both is also set forth in the body of the specification, along with the use of the adapters and locking mechanisms.
To review the scope of the present invention, the variable length elevator link includes a shank, a first link end and a second link end.
The shank has a first collar end and a second collar end with each collar being adapted to connect to a link end. In one embodiment, each collar end may have internal threading to engage each second end of each link end having external threading.
Each link end has a first loop end forming an eye and a second end adapted for connecting to the first and second collar end of the shank. In one of the preferred embodiments, each link end has external threading to engage each shank collar having internal threading.
The method of the present invention allows one to select a shank of any desired length subject only to material strength limitations.
It has also been noted that when desired rotation may be prevented by means of the use of nuts and bolts or screws in the anti-rotation hole drilled through each shank collar engaged with a link end having corresponding holes drilled in its shank end.
There are many methods of connecting the components of the present invention. These techniques range from the easily assembled and disassembled to relatively permanent connections. Interference fits, ball-and-socket, grooves with lock or retaining rings, threads of single or multiple starts, and either straight or tapered pitch diameter, cross pins,jam or lock nuts, keys, and hooks are all alternative connections which may be employed in connection with the components of the present invention. Mechanisms such as nylon rings or inserts or both, anaerobic adhesives, or thread locking compounds may also be used.
It is to be noted that in one of the preferred embodiments a cross-drilled pin is located at or near the free end of the link connection where a hole is drilled through the male member at the end which is not stressed by the axial load. While the mating hole in the shank or adapter is therefore in the xe2x80x9chigh stress zonexe2x80x9d of the shank or the adapter, these parts can be made of a sufficient cross-section or size so as to negate the effect on the part.
Some of the above alternatives may be used for direct connection of the link to the adaptor or to the center section shank, the limitation being the specific dimensions of the connecting means and the material available in the parts.
It is desirable to mate a threaded link end with one, and only one, threaded connection for its usable life, since no two threaded parts have the same characteristics, such as thread pitch. High loads on long, engaged lengths of such threads generally lead to some localized yielding. Changing mating parts would cause additional yielding, as two mating parts are deformed to match each other.
Each additional loading which is accompanied by yielding increases the chance of fatigue damage, which would render the part useless. In general, the connections made to the link ends are intended to be xe2x80x9cmarried for lifexe2x80x9d.
One of the advantages of using an adapter between the shank and the link end is that the adapter can be mated to the link end instead of the shank itself. In other words, the adapter can be threaded as required to mate with the link end xe2x80x9cfor lifexe2x80x9d, with the connection at the opposite end of the adapter being designed and sized for interchanging shank center sections with each link end. For example, this approach could include different thread styles, larger connection size, or a different type of connection, all made possible by the fact that the adapter can be made as desired, and the interchangeable end of the adapter is not limited by the pre-existing size of the link. Once an adapter is fitted to the link ends, a center section can be fitted between the adapters of the opposing link ends.
By manufacturing different length shank center sections, one can produce an unlimited number of specific lengths.
Furthermore, the use of these adapters would allow interchangeable combinations, that is to say, assembling link ends of different nominal sizes or manufacturers or both into one assembly. It is sometimes the case that an elevator of 1000 ton capacity is selected for a string of only 500 tons, not because of the capacity of the elevator, but because of the slips which engage the pipe. Certain slips do less damage to the pipe being linked. However, the drilling rig may be equipped with only a 500 ton hook, which will not accept the larger 1000 ton links. In this case, the elevator links could be assembled with a 500 ton link end at the top in order to engage the hook, and a 1000 ton link end at the lower end in order to engage the elevator.
While one-piece forged links can be special ordered with different ends as described above, they are expensive and involve long delivery times. In general, such one-piece forged links can not be reconverted or reversed in orientation.
One set each of 500, 750, and 1000 ton links, equipped with adapters and a variety of combinations of center section shanks makes possible a large number of combinations and lengths.
Among the inventive features of the present invention are:
A first elevator link, having an elongated shank member comprising a connecting end and a first link end forming an aperture; and a second link having a first loop end forming an aperture and a second end adapted for connecting to the connecting end of the elongated shank member.
These features may also include a first link end which has a first loop end forming an aperture and a second end adapted for connecting to the shank and further means adapted for connecting such as internal threading in the connecting end of the elongated shank member; and external threading of the second end of the link end adapted for connecting to the connecting end of the elongated shank member.
Other means may also be adapted for connecting, such as a cross pin providing a connection between the connecting end of the elongated shank member and the link end.
A locking mechanism may be used in a connection between the elongated shank member and the link to prevent rotation of the link end in relation to the elongated shank member.
An adaptor with a first connecting end and a second connecting end; a link having a second end adapted for connecting being adapted to engage the first connecting end of the adapter; and the connecting end of the elongated shank member being adapted to engage the second connecting end of said adapter, also, is an inventive feature of the present invention, as are a ball-and-socket, grooves with retaining rings. threads of multiple start configurations. threads of tapered pitch diameter, cross pins, interference fits and means employing keys and hooks.
A further aspect of the present invention is the method of making a multi-piece elevator link, which may be of variable length or variable capacity or both, comprising in one way or another providing a unitary one piece elevator link comprising an elongated shank member, a first link end having a loop end forming an aperture, and a second link end having a loop end forming an aperture, said first and second link ends being at opposite ends of the elongated shank member, cutting the elongated shank member into two parts, providing at least one end of the elongated shank member with means adapted for connecting to an end link, and attaching a link end to the means adapted for connecting with the elongated shank member.
The means for connecting may be provided for both link ends, and an adapter may be placed between the elongated shank member and the link end and a means of connection may be provided for the elongated shank member and the link ends including means of connection through the adapter.
Rotation of the link ends with respect to the elongated shank member may be provided for. The end link and the adapter may be connected by means intended to mate them for their useful life. The connection to the elongated shank member allows for a change of the elongated shank member or the end link.
In short, multi-piece elevator links, which may be of variable length or capacity or both, may be produced by cutting a unitary link into two parts and connecting different combinations of shanks and link end to form the desired elevator link. Alternatively, the link ends may be manufactured with a loop end on one end and a connector on the other, the connector capable of connecting to the shank. This eliminates the need for a separate adapter by combining the adapter function with the link end.
Rotation of the link ends with respect to the shank may be prevented. Adapters may be employed between the shank and the link ends to provide varying connections.